Interlayer dielectric and pre-applied die attach adhesive materials

ABSTRACT

The present invention relates to interlayer dielectric materials and pre-applied die attach adhesives, more specifically pre-applied die attach adhesives (such as wafer and other substrate-applied die attach adhesives), methods of applying the interlayer dielectric materials onto substrates to prepare low K dielectric semiconductor chips, methods of applying the pre-applied die attach adhesives onto wafer and other substrate surfaces, and assemblies prepared therewith for connecting microelectronic circuitry.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.10/502,976, filed Jul. 30, 2004 now U.S. Pat. No. 7,312,534, whichclaims the benefit of an earlier filing date from International PatentApplication No. PCT/US2003/19052, filed Jun. 17, 2003, which claims thebenefit of an earlier filing date from U.S. Provisional Application No.60/389,642, filed Jun. 17, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to interlayer dielectric materials andpre-applied die attach adhesives, more specifically pre-applied dieattach adhesives (such as wafer and other substrate-applied die attachadhesives), methods of applying the interlayer dielectric materials ontosubstrates to prepare low K dielectric semiconductor chips, methods ofapplying the pre-applied die attach adhesives onto wafer and othersubstrate surfaces, and assemblies prepared therewith for connectingmicroelectronic circuitry.

2. Brief Description of Related Technology

Bismaleimides occupy a prominent position in the spectrum ofthermosetting resins, and a number of bismaleimides are commerciallyavailable. Bismaleimides have been used for the production of moldingsand adhesive joints, heat-resistant composite materials, and hightemperature coatings. More recently, Henkel Loctite Corporation hascommercialized a number of products based in part on certainbismaleimides for the attachment of semiconductor chips to circuitboards, which have received favorable responses from within themicroelectronic packaging industry. These products are described in oneor more of U.S. Pat. No. 5,789,757 (Husson), U.S. Pat. No. 6,034,194(Dershem), U.S. Pat. No. 6,034,195 (Dershem) and U.S. Pat. No. 6,187,886(Husson).

Low-k dielectric materials (or interlayer dielectrics, “ILD's”) play animportant role in the future development of advanced integrated circuitmanufacturing, enabling the application of copper interconnects insub-0.18 micron fabrication processes. ILD's are used in integratedcircuit manufacturing to insulate copper interconnects from theirsurroundings, ensuring less cross talk between interconnections. Crosstalk is a common problem in integrated circuit manufacturing, as itcauses malfunctions in the circuit. Cross talk becomes even morepronounced as the integrated circuit continues to be designed smallerand smaller. And ILD's are an important aspect of this design trend tomaximize the efficiency of ever more compact Integrated circuits.

Many in the industry even view ILD's as a potential successor to siliconoxide insulators. Little progress has been reported to date, however, atreducing the internal package stresses that lead to the ILD crackingfailures.

It would be desirable therefore to provide ILD's with superiordielectric properties to minimize cross talk. In addition, it would bedesirable to provide electronic packages assembled with such ILD's andmethods of manufacturing such electronic packages that provide enhancedphysical properties.

It would also be desirable to provide die attach adhesive materials in apre-applied form, such as a wafer-applied or substrate-applied versionthereof. Such a version would eliminate many of the storage, dispensing,handling and processing issues that exist when dispensing in a flowableform reactive adhesives, including die attach adhesive materials.

In addition, in more extreme environments, such as those elevatedtemperature conditions to which a semiconductor device may be exposedduring the solder reflow cycle where a lead free solder is used toestablish electrical interconnection, it would be desirable to use inthe pre-applied die attach adhesive material a material which is evenmore robust than the maleimides to which reference is made above.

Pre-applied adhesives themselves are not a new commercial product. Forinstance, Henkel Loctite has a substantial business in pre-appliedthreadlocker adhesives, which involve (meth)acrylate chemistry, for usein connection with nut and bolt assemblies, curable by either aphotocure mechanism, a heat cure mechanism, or combinations thereof,with an optional secondary anaerobic cure mechanism. See alsoInternational Patent Application No. PCT/US00/107494; and U.S. Pat. Nos.2,928,446, 4,325,985, 4,632,944 and 5,300,608.

However, to date there has not been an article of manufacture placed incommerce, such as a semiconductor chip or a semiconductor wafer, with adie attach adhesive material pre-applied thereon for application withoutthe Intermediate process steps attendant with a flowable die attachadhesive material, particularly where the reactive component of theadhesive material is based in whole or in part on a bismaleimide or formore extreme environments where the reactive component of the die attachadhesive material is based in whole or in part on a benzoxazine.

SUMMARY OF THE INVENTION

The present invention in one aspect is directed to an article ofmanufacture, and in particular, a semiconductor chip (or a chip die)provided for attachment to and electrical interconnection with a carriersubstrate. The semiconductor chip has a first surface and a secondsurface, with the first surface having electrical contacts arranged in apredetermined pattern thereon for providing electrical engagement with acarrier substrate, and with the second surface having a pre-applied dieattach adhesive material disposed on a layer or a portion thereof,preferably as a film.

Alternatively, the semiconductor chip may be in a wafer form; that is,in a bulk form, from which individual semiconductor chips may be dicedfrom the wafer.

In one embodiment of this aspect of the invention, the die attachadhesive material desirably includes a maleimide-, itaconamide- ornadimide-containing compound in liquid form or solid form, which when inliquid form is used in combination with a thermoplastic elastomer andwhen in solid form optionally includes the thermoplastic elastomer. Thedie attach adhesive material may include additional materials that areeither co-curable with the maleimide-, itaconamide- ornadimide-containing compound, such as a (meth)acrylate-functionalizedmaterial, a vinyl-functionalized material, a vinyl ether-functionalizedmaterial and the like.

When a maleimide-, itaconamide- or nadimide-containing compound is usedin liquid form is in the pre-applied die attach adhesive material, itmay be B-staged, such as by exposure to radiation in electromagneticspectrum, to render it non-flowable prior to ultimate cure.

As noted, the die attach adhesive material may include maleimide-,itaconamide- or nadimide-containing compound, in a liquid form or asolid form.

Like Henkel Loctite's bismaleimide die attach adhesive materials thatare sold in liquid form, the Inventive pre-applied die attach adhesivematerials produce cured die attach composition exhibiting a combinationof highly desirable physical properties, including rapid curing, lowwater absorption and low dielectric constant. And the inventive articlesof manufacture pre-applied with the type of adhesive materials generallyreferred to above have the added advantage of being useful without theordinary processing steps taken when working with a flowable adhesivematerial, otherwise designed for similar applications.

In another aspect of the invention, the die attach adhesive materialdesirably includes a benzoxazine-containing compound.

The present invention provides advantages relating to the avoidance ofdispensing, handling and storage issues for the end user seeking toassemble in particular microelectronic devices using a semiconductorchip having an adhesive material pre-applied to a surface thereof.

The invention further provides a method for assembling a semiconductordevice, which includes providing an semiconductor chip with such a dieattach adhesive material, mating the semiconductor chip with a carriersubstrate to form a mated assembly; and exposing the mated assembly totemperature conditions sufficient to cure the die attach adhesivematerial, thereby adhering the semiconductor chip to the carriersubstrate. Alternatively or additionally, the die attach material may bepre-applied onto one or more metallized contact, or bond, pads locatedon the carrier substrate, such as another chip die or a circuit board.The curing conditions for a maleimide-, itaconamide- ornadimide-containing pre-applied die attach adhesive material inaccordance with this invention may involve exposure to a temperature inthe range of about 150° C. up to about 200° C. for a period of time ofabout 0.25 minutes up to about 2 minutes.

In addition, in another aspect the invention provides interlayerdielectric materials, based either on maleimide-, itaconamide- ornadimide-containing compounds or on benzoxazine-containing compounds,and semiconductor chips manufactured therewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a pre-applied die attachsemiconductor chip in one embodiment of the present invention, prior toassembly with a substrate.

FIG. 2 is a schematic representation of a circuit assembly including thesemiconductor chip of FIG. 1 assembled to a substrate.

FIG. 3 is a schematic representation of a circuit assembly including asemiconductor chip assembled to a chip scale package in a furtherembodiment of the present invention.

FIG. 4 is a schematic representation of a wafer backside application.

FIG. 5 is a schematic representation of a wafer backside application.

FIG. 6 is a schematic representation of a substrate application.

FIG. 7 is a schematic representation of a semiconductor chip with aninterlayer dielectric material.

FIG. 8 is a schematic representation of a stacked die application, wherethe upper semiconductor chip is pre-applied with die attach adhesivematerial.

FIG. 9 is a schematic representation of a pre-applied die attach carriersubstrate in one embodiment of the present invention prior to assemblywith a semiconductor chip.

FIG. 10 is a schematic representation of a stacked die application,where the lower semiconductor chip is pre-applied with die attachadhesive material.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings in which like reference characters refer tolike parts throughout the several views thereof, a pre-applied dieattach adhesive material is shown and described in connection with acircuit assembly 50, as depicted in FIGS. 1 and 2. Generally speaking,circuit assembly 50 includes a semiconductor chip in the form ofpre-applied die attach circuit chip 60, and a carrier substrate, such ascircuit board substrate circuit 70.

The pre-applied die attach circuit chip 60 may be attached to carriersubstrates other than a circuit board substrate, such as a heat slug orheat sink, or a heat spreader. The heat slug, heat sink or heat spreadermay be constructed at least in part from materials used for dissipatingheat, such as AlSiC, anodized aluminum and the like.

Circuit chip 60 includes a chip die 62. Semiconductor chip, or chip die,62 may be constructed of any material known in the art, as silicon,germanium, or the like. Chip die 62 may also be coated with a material,which is capable of passivating environmental corrosion, such as apolyimide-, polybenzocyclobutane-, or silicon nitride-based material.The is passivation coating is not shown in FIG. 1 or 2.

Substrate 70 may also be constructed of any material known in the art,such as ceramic substrates including Al₂O₃, SiN₃, and Al₂O₃—SiO₂;substrates or tapes of heat-resistant resins, such as polyimides;substrates of glass-reinforced epoxy; substrates offacrylonitrile-butadiene-styrene (“ABS”); phenolic substrates, and thelike. Substrate 70 includes circuitry on a substrate surface 74,including a plurality of electrical contact pads 76.

Chip die 62 includes opposing first and second surfaces, including chipsurface 64 as a first surface and attach surface 68 as a second surface.Circuitry is provided on chip surface 64, including a plurality ofelectrical contact pads, such as metallized contact pads 66, which arearranged in a pre-determined pattern. These electrical contact pads areconnectable to the contact pads 76 of the substrate 70. The electricalinterconnection and engagement between the circuitry on chip die 62 andthe circuitry on substrate 70 is provided by way of bonds between eachof contact pads 66 on chip die 62 and contact pads 76 of substrate 70,established such as by wire(s) 80. Electrical interconnection can beestablished by bonding wire 80 to contact pads 76 before or, morepreferably, after curing of the die attach material. While the presentfigures depict two wires 80 bonded on chip die 62 and two correspondingcontact pads 76 on substrate 70 for purposes of demonstrating thepresent invention, it is understood that the number of wire bonds andcontact pads 76 may be varied according to the particular desired useand the particular configuration of the circuit chip, and the specificconfiguration depicted herein should not be considered as limiting ofthe present invention.

In the present invention, chip die 62 includes metallized electricalcontacts in the form of contact pads 66 on chip surface 64, and includesdie attach adhesive material 90 pre-applied on the opposing attachsurface 68 prior to assembly of chip die 62 with substrate 70.

The electrical conductor may be bumps, and the solder may besubstantially free of lead, as is the growing trend in the industry.Pre-applied die attach adhesive material 90 provides circuit assembly50, after exposure to appropriate curing conditions, with high adhesivestrength for adhering chip die 62 to substrate 70. Ordinarily, suchadherence occurs by forming a fully cured material in a solid form forattaching and adhering chip die 62 to substrate 70, through exposure toelevated temperature conditions sufficient to promote curing of the dieattach material 90.

The present invention further provides circuit assembly 50 in anassembled form, as depicted in FIG. 2, in which chip die 62 has beenmated with substrate 70, and exposed to appropriate conditions to causedie attach material 90 to attach and adhere chip die 62 to substrate 70.Also, chin die 62 can then be electrically interconnected with substrate70 through an electrical interconnection established between contactpads 66 and contact pads 76, such as by soldering or otherwise bondingwires 80 therebetween.

The present invention thus provides, in one embodiment, an article ofmanufacture in the form of a circuit chip having a first surface capableof providing electrical engagement with a carrier substrate to which itis intended to be electrically interconnected, and a second surface,opposed from the first, and having a pre-applied die attach adhesivematerial disposed on at least a portion thereof. Providing the dieattach adhesive material directly onto a surface of the chip die,eliminates production issues with dispensing volumes and temperatures,and storage, handling and shelf life issues, as well. That is, the enduser of the pre-applied die attach adhesive material no longer needs touse sophisticated dispensing equipment and low temperature storagecontainers for application of such materials. Instead, the end user cannow use either a semiconductor chip or a semiconductor wafer with dieattach adhesive material preapplied onto at least a portion of a surfacethereof, according to the invention and assemble the semiconductordevice with increased ease and throughput.

A semiconductor chip pre-applied with a die attach adhesive materialalso enables the end user to implement tighter package design criteria.That is, because of reduced flowout and bleed from such pre-applied dieattach adhesive materials as contrasted to known adhesives, tightertolerances between die edge and bond may be realized. In addition,semiconductor chips may now be more readily stacked [see e.g., U.S. Pat.No. 5,140,404 (Fogal), U.S. Pat. No. 5,177,632 (Fogal), U.S. Pat. No.5,323,060 (Fogal) and U.S. Pat. No. 6,465,893 (Khandros)], such that theoverall size of the semiconductor device may be reduced, or at leastremain substantially the same in the length and width directions, yetthe performance capabilities of the stacked semiconductor chips may beincreased dramatically. (See FIGS. 8 and 10.)

Moreover, whereas a conventional die attach adhesive material requirestighter controls to avoid kerf creep and contact bond pad contaminationduring bonding of thin dice, no such precautions are necessary whenpre-applied die attach adhesives are used.

The pre-applied adhesive material may also be used to replace the soldermask coating over the die pad, i.e., the pre-applied adhesive servesboth as a carrier substrate, such as a circuit board, protector and asan adhesive. Since the thickness of die stackup is thinner by the amountof the solder mask thickness, this approach enable even thinnersemiconductor device packages to be manufactured.

The die attach material is pre-applied either (a) onto at least aportion of the opposed surface of the circuit chip (FIG. 1) or (b) ontoat least a portion of the carrier substrate between electrical contactpads 76 (FIG. 9), at any thickness or amount which can achievesufficient adhesion between the chip die and the substrate and whichprovides for appropriate properties therebetween during use of the thusintegrated assembly.

The pre-applied die attach material may in one aspect of the inventionbe a thermosetting resin composition which includes in one embodiment amaleimide-containing compound in liquid form, such as is described andclaimed in U.S. Pat. No. 5,789,757 (Husson), U.S. Pat. No. 6,034,194(Dershem), U.S. Pat. No. 6,034,195 (Dershem) and U.S. Pat. No. 6,187,886(Husson), the disclosures of each of which are hereby incorporatedherein by reference. In another embodiment, pre-applied die attachmaterial includes an itaconamide- or nadimide-containing compound.

As noted above, the pre-applied die attach adhesive material may includeadditional materials that are co-curable with the maleimide-,itaconamide- or nadimide-containing compound, such as a(meth)acrylate-functionalized material, a vinyl-functionalized material,a vinyl ether-functionalized material and the like, and/or thermoplasticelastomers that aid in forming a film when mixed with the maleimide-,itaconamide- or nadimide-containing compound.

Described here in the context of a pre-applied die attach semiconductorchip (rather than for instance a stacked die application or pre-applieddie attach carrier substrate), prior to disposal onto the second surfaceof the semiconductor chip or wafer, the die attach adhesive materialshould be in the flowable form. Thus, when a maleimide-, itaconamide- ornadimide-containing compound is used that is in liquid form, theresulting die attach adhesive material should be flowable. When amaleimide-, itaconamide- or nadimide-containing compound is used insolid form, it is desirable to either warm the semiconductor chip or thewafer the die attach adhesive material, or to mix with a diluent, eitherof the reactive or inert variety, to form a solution of dispersionthereof and then dispose such solution or dispersion onto the secondsurface of the semiconductor chip or wafer.

The pre-applied die attach adhesive material may also include at leastone cure initiator for the maleimide-, itaconamide- ornadimide-containing compound.

The maleimides, nadimides, and itaconimides include those compoundshaving the following structures I, II and III, respectively

where:

m=1-15,

p=0-15,

each R² is independently selected from hydrogen or lower alkyl, and

J is a monovalent or a polyvalent moiety comprising organic ororganosiloxane radicals, and combinations of two or more thereof.

More specific representations of the maleimides, itaconimides andnadimides include those corresponding to structures I, II, or III, wherem=1-6, p=0, R² is independently selected from hydrogen or lower alkyl,and J is a monovalent or polyvalent radical selected from hydrocarbyl,substituted hydrocarbyl heteroatom-containing hydrocarbyl, substitutedheteroatom-containing hydrocarbyl, hydrocarbylene, substitutedhydrocarbylene, heteroatom-containing hydrocarbylene, substitutedheteroatom-containing hydrocarbylene, polysiloxane,polysiloxane-polyurethane block copolymer, and combinations of two ormore thereof, optionally containing one or more linkers selected from acovalent bond, —O—, —S—, —NR—, —O—C(O)—, —O—C(O)—O—, —O—C(O)—NR—,—NR—C(O)—, —NR—C(O)—O—, —NR—C(O)—NR—, —S—C(O)—, —S—C(O)—O—, —S—C(O)—NR—,—S(O)—, —S(O)₂—, —O—S(O)₂—, —O—S(O)₂—O—, —O—S(O)₂—NR—, —O—S(O)—,—O—S(O)—O—, —O—S(O)—NR—, —O—NR—C(O)—, —O—NR—C(O)—O—, —O—NR—C(O)—NR—,—NR—O—C(O)—, —NR—O—C(O), —O—, —NR—O—C(O)—NR—, —O—NR—C(S)—,—O—NR—C(S)—O—, —O—NR—C(S)—NR—, —NR—O—C(S)—, —NR—O—C(S)—O—,—NR—O—C(S)—NR—, —O—C(S)—, —O—C(S)—O—, —O—C(S)—NR—, —NR—C(S)—,—NR—C(S)—O—, —NR—C(S)—NR—, —S—S(O)₂—, —S—S(O)₂—O—, —S—S(O)₂—NR—,—NR—O—S(O)—, —NR—O—S(O)—O—, —NR—O—S(O)—NR—, —NR—O—S(O)₂—,—NR—O—S(O)₂—O—, —NR—O—S(O)₂—NR—, —O—NR—S(O)—, —O—NR—S(O)—O—,—O—NR—S(O)—NR—, —O—NR—S(O)₂—O—, —O—NR—S(O)₂—NR—, —O—NR—S(O)₂—,—O—P(O)R₂—, —S—P(O)R₂—, —NR—P(O)R₂—, where each R is independentlyhydrogen, alkyl or substituted alkyl, and combinations of any two ormore thereof.

When one or more of the above described monovalent or polyvalent groupscontain one or more of the above described linkers to form the “J”appendage of a maleimide, nadimide or itaconimide group, as readilyrecognized by those of skill in the art, a wide variety of linkers canbe produced, such as, for example, oxyalkyl, thioalkyl, aminoalkyl,carboxylalkyl, oxyalkenyl, thioalkenyl, aminoalkenyl, carboxyalkenyl,oxyalkynyl, thioalkynyl, aminoalkynyl, carboxyalkynyl, oxycycloalkyl,thiocycloalkyl, aminocycloalkyl, carboxycycloalkyl, oxycloalkenyl,thiocycloalkenyl, aminocycloalkenyl, carboxycycloalkenyl, heterocyclic,oxyheterocyclic, thioheterocyclic, aminoheterocyclic,carboxyheterocyclic, oxyaryl, thioaryl, aminoaryl, carboxyaryl,heteroaryl, oxyheteroaryl, thioheteroaryl, aminoheteroaryl,carboxyheteroaryl, oxyalkylaryl, thioalkylaryl, aminoalkylaryl,carboxyalkylaryl, oxyarylalkyl, thioarylalkyl, aminoarylalkyl,carboxyarylalkyl, oxyarylalkenyl, thioarylalkenyl, aminoarylalkenyl,carboxyarylalkenyl, oxyalkenylaryl, thioalkenylaryl, aminoalkenylaryl,carboxyalkenylaryl, oxyarylalkynyl, thioarylalkynyl, aminoarylalkynyl,carboxyarylalkynyl, oxyalkynylaryl thioalkynylaryl, aminoalkynylaryl orcarboxyalkynylaryl, oxyalkylene, thioalkylene, aminoalkylene,carboxyalkylene, oxyalkenylene, thioalkenylene, aminoalkenylene,carboxyalkenylene, oxyalkynylene, thioalkynylene, aminoalkynylene,carboxyalkynylene, oxycycloalkylene, thiocycloalkylene,aminocycloalkylene, carboxycycloalkylene oxycycloalkenylene,thiocycloalkenylene, aminocycloalkenylene, carboxycycloalkenylene,oxyarylene, thioarylene, aminoarylene, carboxyarylene, oxyalkylarylene,thioalkylarylene, aminoalkylarylene, carboxyalkylarylene,oxyarylalkylene, thioarylalkylene, aminoarylalkylene,carboxyarylalkylene, oxyarylalkenylene, thioarylalkylene,aminoarylalkenylene, carboxyarylalkenylene, oxyalkenylarylene,thioalkenylarylene, aminoalkenylarylene, carboxyalkenylarylene,oxyarylalkynylene, thioarylalkynylene, aminoarylalkynylene, carboxyarylalkynylene, oxyalkynylarylene, thioalkynylarylene,aminoalkynylarylene, carboxyalkynylarylene, heteroarylene,oxyheteroarylene, thioheteroarylene, aminoheteroarylene,carboxyheteroarylene, heteroatom-containing di- or polyvalent cyclicmoiety, oxyheteroatom-containing di- or polyvalent cyclic moiety,thioheteroatom-containing di- or polyvalent cyclic moiety,aminoheteroatom-containing di- or polyvalent cyclic moiety,carboxyheteroatom-containing di- or polyvalent cyclic moiety, disulfide,sulfonamide, and the like.

In another embodiment, maleimides, nadimides, and itaconimidescontemplated for use in the practice of the present invention have thestructures I, II, and III, where m=1-6, p=0-6, and J is selected fromsaturated straight chain alkyl or branched chain alkyl, optionallycontaining optionally substituted aryl moieties as substituents on thealkyl chain or as part of the backbone of the alkyl chain, and where thealkyl chains have up to about 20 carbon atoms;

a siloxane having the structure:—(C(R³)₂)_(d)—[Si(R⁴)₂—O]_(f)—Si(R⁴)₂—(C(R³)₂)_(e)—,—(C(R³)₂)_(d)—C(R³)—C(O)O—(C(R³)₂)_(d)—[Si(R⁴)₂—O]_(f)—Si(R⁴)₂—(C(R³)₂)_(e)—O(O)C—(C(R³)₂)_(e)—,or—(C(R³)₂)_(d)—C(R³)—O(O)C—(C(R³)₂)_(d)—[Si(R⁴)₂—O]_(f)—Si(R⁴)₂—(C(R³)₂)_(e)—C(O)O—(C(R³)₂)_(e)—,where:

each R³ is independently hydrogen, alkyl or substituted alkyl,

each R⁴ is independently hydrogen, lower alkyl or aryl,

d=1-10,

e=1-10, and

f=1-50;

a polyalkylene oxide having the structure:[(CR₂)_(r)—O—]_(f)—(CR₂)_(s)—where:

each R is independently hydrogen, alkyl or substituted alkyl,

r=1-10,

s=1-10, and

f is as defined above;

aromatic groups having the structure:

where:

each Ar is a monosubstituted, disubstituted or trisubstituted aromaticor heteroaromatic ring having in the range of 3 up to 10 carbon atoms,and

Z is:

-   -   saturated straight chain alkylene or branched chain alkylene,        optionally containing saturated cyclic moieties as substituents        on the alkylene chain or as part of the backbone of the alkylene        chain, or    -   polyalkylene oxides having the structure:        —[(CR₂)_(r)—O—]_(q)—(CR₂)_(s)—

where:

-   -   each R is independently hydrogen, alkyl or substituted alkyl, r        and s are each defined as above, and    -   q falls in the range of 1 up to 50;    -   di- or tri-substituted aromatic moieties having the structure:

where:

each R is independently hydrogen, alkyl or substituted alkyl,

t falls in the range of 2 up to 10,

u falls in the range of 2 up to 10, and

Ar is as defined above;

-   -   aromatic groups having the structure:

where:

each R is independently hydrogen, alkyl or substituted alkyl,

t=2-10,

k=1, 2 or 3,

g=1 up to about 50,

each Ar is as defined above,

E is —O— or —NR⁵—, where R⁵ is hydrogen or lower alkyl; and

W is straight or branched chain alkyl, alkylene, oxyalkylene, alkenyl,alkenylene, oxyalkenylene, ester, or polyester, a siloxane having thestructure —(C(R³)₂)_(d)—[Si(R⁴)₂—O]_(f)—Si(R⁴)₂—(C(R³)₂)_(e)—,—(C(R³)₂)_(d)—C(R³)—C(O)O—(C(R³)₂)_(d)—[Si(R⁴)₂—O]_(f)—Si(R⁴)₂—(C(R³)₂)_(e)—O(O)C—(C(R³)₂)_(e)—,or—(C(R³)₂)_(d)—C(R³)—O(O)C—(C(R³)₂)_(d)—[Si(R⁴)₂—O]_(f)—Si(R⁴)₂—(C(R³)₂)_(e)—C(O)O—(C(R³)₂)_(e)—,where;

-   -   each R³ is independently hydrogen, alkyl or substituted alkyl,    -   each R⁴ is independently hydrogen, lower alkyl or aryl,    -   d=1-10,    -   e=1-10, and    -   f=1-50;    -   a polyalkylene oxide having the structure:        —[(CR₂)_(r)—O—]_(f)—(CR₂)_(s)—        where:

each R is independently hydrogen, alkyl or substituted alkyl,

r=1-10,

s=1-10, and

f is as defined above;

optionally containing substituents selected from hydroxy, alkoxy,carboxy, nitrile, cycloalkyl or cycloalkenyl;

a urethane group having the structure:R⁷—U—C(O)—NR⁶—R⁸—N⁶—C(O)—(O—R⁸—O—C(O)—NR⁶—R⁸—NR⁶—C(O))_(v)—U—R⁸—where:

each R⁶ is independently hydrogen or lower alkyl,

each R⁷ is independently an alkyl, aryl, or arylalkyl group having 1 to18 carbon atoms,

each R⁸ is an alkyl or alkyloxy chain having up to about 100 atoms inthe chain, optionally substituted with Ar,

U is —O—, —S—, —N(R)—, or —P(L)_(1,2)—,

where R as defined above, and where each L is independently ═O, ═S, —ORor —R; and

v=0-50;

-   -   polycyclic alkenyl; or mixtures of any two or more thereof.

When in the liquid state, the maleimide-, nadimide- and/oritaconimide-containing compounds have functional group attached to amonovalent radical, J, or separated by a polyvalent radical, J, each ofthe monovalent radical or the polyvalent radical having sufficientlength and branching to render the maleimide-, nadimide- and/oritaconimide-containing compound a liquid.

In a more specific recitation of such maleimide-, nadimide-, andItaconimide-containing compounds of structures I, II and III,respectively, each R is independently hydrogen or lower alkyl, -J-comprises a branched chain alkyl, alkylene, alkylene oxide, alkylenecarboxyl or alkylene amido species having sufficient length andbranching to render the maleimide, nadimide and/or itaconimide compounda liquid, and m is 1, 2 or 3.

The maleimide-containing compound may be chosen from those described andclaimed in U.S. Pat. No. 5,789,757 (Husson), U.S. Pat. No. 6,034,194(Dershem), U.S. Pat. No. 6,034,195 (Dershem) and U.S. Pat. No. 6,187,886(Husson), the disclosures of each of which are hereby incorporatedherein by reference, and those described by U.S. Pat. No. 6,063,828(Ma), U.S. Pat. No. 6,265,530 (Herr), U.S. Pat. No. 6,281,314 (Tong) andU.S. Pat. No. 6,316,566 (Ma), the disclosures of each of which arehereby incorporated herein by reference, as well.

As employed herein,

“alkyl” refers to hydrocarbyl radicals having 1 up to about 20 carbonatoms, preferably 2-10 carbon atoms; and “substituted alkyl” comprisesalkyl groups further bearing one or more substituents selected fromhydroxy, alkoxy, mercapto, cycloalkyl, substituted cycloalkyl,heterocyclic, substituted heterocyclic, aryl, substituted aryl,heteroaryl, substituted heteroaryl, aryloxy, substituted aryloxy,halogen, cyano, nitro, amino, amido, C(O)H, acyl, oxyacyl, carboxyl,carbamate, sulfonyl sulfonamide, sulfuryl, and the like;

“cycloalkyl” refers to cyclic ring-containing groups containing in therange of 3 up to about 8 carbon atoms, and “substituted cycloalkyl”refers to cycloalkyl groups further bearing one or more substituents asset forth above;

“alkenyl” refers to straight or branched chain hydrocarbyl groups havingat least one carbon-carbon double bond, and having in the range of 2 upto about 12 carbon atoms, and “substituted alkenyl” refers to alkenylgroups further bearing one or more substituents as set forth above;

“cycloalkenyl” refers to cyclic ring-containing groups containing in therange of 3 up to about 8 carbon atoms, and “substituted cycloalkenyl”refers to cycloalkenyl groups further bearing one or more substituentsas set forth above;

“alkylene” refers to divalent hydrocarbyl radicals having 1 up to about20 carbon atoms, preferably 2-10 carbon atoms and “substituted alkylene”comprises alkylene groups further bearing one or more substituents asset forth above;

“oxyalkylene” refers to an alkylene moiety wherein one or more of themethylene units of the alkylene moiety has been replaced with an oxygenatom;

“aryl” refers to aromatic groups having in the range of 6 up to about 14carbon atoms and “substituted aryl” refers to aryl groups furtherbearing one or more substituents as set forth above;

“alkenylene” refers to divalent, straight or branched chain hydrocarbylgroups having at least one carbon-carbon double bond, and having in therange of 2 up to about 12 carbon atoms, and “substituted alkenylene”refers to alkenylene groups further bearing one or more substituents asset forth above; and

“oxyalkenylene” refers to an alkenylene moiety wherein one or more ofthe methylene units of the alkenylene moiety has been replaced with anoxygen atom.

Particularly desirable maleimides compounds for use in the pre-applieddie attach adhesive material or interlayer dielectric materialscontemplated for use in the practice of the present invention include,for example, maleimides having the following structures:

Preferred maleimide resins of structure I include stearyl maleimide,oleyl maleimide and behenyl maleimide,1,20-bismaleimido-10,11-di-octyl-eicosane, and the like, as well ascombinations thereof.

In another aspect of the invention, the pre-applied die attach adhesivematerial may include a benzoxazine-containing compound.

Where the pre-applied die attach adhesive material includes abenzoxazine-containing compound, the pre-applied die attach adhesivematerial may also include (ii) an epoxy resin or episulfide resincomponent; (iii) one or more of an oxazoline component, a cyanate estercomponent, a phenolic component, a thiophenolic component, anacrylonitrile-butadiene copolymer component, polyimide component, and apolyimide/siloxane component, and (iv) optionally, a curative. Whenthese additional components are employed together with the benzoxazinein the pre-applied die attach adhesive material, it is particularlydesirable that where an epoxy is present, component (iii) is present andis not solely a phenolic component.

The benzoxazine may be chosen from a host of materials including:

where:

L is an optional spacer, such as an alkylene or a siloxane linkingmoiety, hydrogen, a direct bond, O, C═O, S, O═S═O, C, CH, CH₂, CR⁹R¹⁰and R⁹ and R¹⁰ are alkyl, halogen substituted alkyl, aryl or alkaryl;

Ar is optionally substituted arylene;

Q is an oxazine ring or amine salt thereof having the structure:

and is bonded to Ar in a fused manner at positions 5 and 6 of theoxazine ring,

where:

-   -   Sp is optional, and if present, is a C₁ to C₆ alkylene    -   spacer,    -   n is 1 or 2,    -   m is optional, and if present, is 1 to 4,    -   x and y are each independently 0 to 4, and    -   at least one of R¹¹, R¹², or R¹³ is a polymerizable moiety, such        as a benzoxazine represented by L-(Ar(Q_(n)))_(m).

The benzoxazine may also be embraced by structure:R¹¹ _(x)—Ar(Q)_(n)  VIwhere:

Ar is optionally substituted arylene,

Q is an oxazine ring or amine salt thereof having the structure:

and is bonded to Ar in a fused manner at positions 5 and 6 of theoxazine ring,

Sp is optional, and if present, is a C₁ to C₆ alkylene spacer,

n is 1 or 2,

x and y are each independently 0 to 4, and

at least one of R¹¹, R¹², or R¹³ is a polymerizable moiety.

In addition, the benzoxazine may be embraced by

where o is 1-4, X is a direct bond (when o is 2), alkyl (when o is 1),alkylene (when o is 2-4), carbonyl (when o is 2), thiol (when o is 1),thioether (when o is 2), sulfoxide (when o is 2), and sulfone (when o is2), and R¹⁴ is alkyl, such as methyl, ethyl, propyls and butyls, oraryl.

In a more specific embodiment, the benzoxazine component is embraced by

where X is selected from the group consisting of a direct bond, CH₂,C(CH₃)₂, C═O, S═O and O═S═O, S, and R¹⁴ and R¹⁵ are the same ordifferent and are selected from methyl, ethyl, propyls, or butyls andaryl.

In yet a more specific embodiment, the benzoxazine component is embracedby

where R¹⁴ and R¹⁵ are the same or different and are selected frommethyl, ethyl, propyls, butyls or aryl.

The benzoxazine component may include one or more of

where R¹⁴, R¹⁵ and R¹⁶ are the same or different and are selected frommethyl, ethyl, propyls, butyls or aryl.

For instance, specific multifunctional benzoxazines include

Thus, the benzoxazine component may include multifunctionalbenzoxazines, monofunctional benzoxazines, and combinations thereof.

The monofunctional benzoxazine comprises

where R¹⁴ is selected from methyl ethyl, propyls, butyls or aryl, suchas methyl.

When a diluent is added, it is desirable for the diluent to be areactive diluent which, in combination with the maleimide-, nadimide-,and itaconimide-containing compound or benzoxazine-containing compound,forms a thermosetting resin composition. Such reactive diluents includeacrylates and methacrylates of monofunctional and polyfunctionalalcohols, vinyl compounds as described in greater detail herein,styrenic monomers (i.e., ethers derived from the reaction of vinylbenzyl chlorides with mono-, di-, or trifunctional hydroxy compounds),and the like.

An especially preferred class of reactive diluents corresponding tovinyl or polyvinyl compounds comprise the general formula:

where q is 1, 2 or 3,

each R is independently selected from hydrogen or lower alkyl,

each Q is independently selected from ether, ketone, ester or reverseester, and

Y is a monovalent moiety or a multivalent linking moiety.

The multivalent linking Y is typically selected from J above.

Exemplary vinyl or polyvinyl compounds embraced by the above genericstructure include stearyl vinyl ether, behenyl vinyl ether, eicosylvinyl ether, isoeicosyl vinyl ether, isotetracosyl vinyl ether,poly(tetrahydrofuran) divinyl ether, tetraethylene glycol divinyl ether,tris-2,4,6-(1-vinyloxybutane-4-oxy-1,3,5-triazine,bis-1,3-(1-vinyloxybutane-4)-oxycarbonyl-benzene (alternately referredto as bis(4-vinyloxybutyl)isophthalate; available from HoneywellInternational Inc., Morristown, N.J., under the trade name “VECTOMER”4010), divinyl ethers prepared by transvinylation between lower vinylethers and higher molecular weight di-alcohols, in the presence of asuitable palladium catalyst, optionally hydrogenated disubstitutedpolybutadienes, optionally hydrogenated disubstituted polyisoprenes,optionally hydrogenated disubstituted poly[(1-ethyl)-1,2-ethane], andthe like. Preferred divinyl resins include stearyl vinyl ether, behenylvinyl ether, eicosyl vinyl ether, isoeicosyl vinyl ether,poly(tetrahydrofuran) divinyl ether, divinyl ethers prepared bytransvinylation between lower vinyl ethers and higher molecular weightdi-alcohols, in the presence of a suitable palladium catalyst, and thelike.

Additionally, divinyl compounds corresponding to structure XXIV where-Q- is an ester and Y is a high molecular weight branched chain alkylenespecies having from about 12 to about 500 carbon atoms are usefulthermosetting resin compositions, even in the absence of bismaleimideresins. When combined with suitable amounts of at least one free radicalinitiator and at least one coupling agent, these divinyl ether resins,alone, are capable of forming thermosetting resin compositionsexhibiting excellent physical properties, including rapid cure rates andlow water absorption.

Of course, the die attach material may include combinations of a vinylcompound of structure XXIV and a maleimide-, nadimide-, oritaconimide-containing compound or benzoxazine-containing compound, soas to benefit from the highly desirable combination of physicalproperties, including both rapid cure rates and low water absorption.

Desirably, the pre-applied die attach adhesive material may furtherinclude a thermoplastic elastomer which is co-curable therewith,particularly when the maleimides, itaconamides and nadimides are in theliquid form. As employed herein, “co-curable” refers to the ability of athermoplastic elastomer to undergo copolymerization with a macromonomersuch as the maleimide, itaconamide and nadimide containing compound toform a three-dimensional polymeric network.

Thermoplastic elastomers contemplated for use in the practice of thepresent invention are typically block copolymers. The block copolymershaving at least one unit of the general formula (A-B) or (A-B-A),wherein A is a non-elastomeric polymer block and B is an elastomericpolymer block. Block copolymers contemplated for use in the practice ofthe present invention preferably have low dielectric constants. Inaddition, the thermoplastic include pendant and/or terminal units ofethylenic unsaturation, and therefore are able to cure with othercomponents in the die attach material.

The non-elastomeric polymer block (A) may be the polymerization productof one or more optionally substituted aromatic hydrocarbons containingat least one unit of ethylenic unsaturation. Aromatic hydrocarbonscontemplated for use in the practice of the present invention include,for example, optionally substituted styrene, optionally substitutedstilbene, and the like. Substituents contemplated for optional use inthe practice of the present invention include for example, alkyl,alkenyl, alkynyl, hydroxy, alkoxy, alkenoxy, and the like. In apreferred embodiment, the aromatic hydrocarbon is optionally substitutedstyrene.

The elastomeric polymer block (B) is typically the polymerization orcopolymerization product of optionally substituted olefin monomersand/or optionally substituted conjugated diene monomers. Olefin monomerscontemplated for use in the practice of the present invention typicallycontain from 2 up to about 20 carbon atoms. Preferably, the olefinmonomers contain from 2 up to about 12 carbon atoms. In a particularlypreferred embodiment, the olefin monomers include, for example,ethylene, propylene, butylene, isobutylene, acrylonitrile,(meth)acrylate, and the like. Most preferably, the olefin monomer isacrylonitrile.

Conjugated diene monomers contemplated for use in the practice of thepresent invention typically contain from 4 up to about 20 carbon atoms.Preferably, the conjugated diene monomers contain from 4 up to about 12carbon atoms. In a particularly preferred embodiment, the conjugateddiene monomers include, for example, butadiene, isoprene,dimethylbutadiene, and the like. Most preferably, the conjugated dienemonomer is butadiene.

Thermoplastic elastomers contemplated for use include, for example,polystyrene-polybutadiene-polystyrene block copolymers,polystyrene-polyisoprene-polystyrene block copolymers,polystyrene-polydimethylbutadiene-polystyrene block copolymers,polybutadiene-polyacrylonitrile block copolymers, and the like.Preferably, the block copolymer is apolystyrene-polybutadiene-polystyrene block copolymer or apolybutadiene-polyacrylonitrile block copolymer.

When a thermoplastic elastomer is employed, the die attach materialtypically contains in the range of about 10 wt % up to about 95 wt %thermoplastic elastomer, in the range of about 5 wt % up to about 90 wt% of the maleimide-, itaconamide- or nadimide-containing compound, orthe benzoxazine-containing compound, and in the range of about 0.2 wt %up to about 2.0 wt % a cure initiator, where wt % is based on the totalweight of the composition. Preferably, the maleimide-, itaconamide- ornadimide-containing compound, or the benzoxazine-containing compound, ispresent from about 10 wt % to about 80 wt %.

A cure initiator may also be included, and when included desirably is afree radical initiator, triggered either by exposure to temperatures inthe range of about 70° C. to about 180° C., or to radiation in theelectromagnetic spectrum. As employed herein, the term “free radicalinitiator” refers to any chemical species which, upon exposure tosufficient energy (e.g., light, heat, or the like), decomposes into atleast two species which are uncharged, but which each possesses at leastone unpaired electron.

Thermal free-radical cure initiators include for example, peroxides(e.g., peroxy esters, peroxy carbonates, hydroperoxides, alkylperoxides,arylperoxides, and the like), azo compounds, and the like. Presentlypreferred peroxides contemplated for use in the practice of the presentinvention include dicumyl peroxide, dibenzoyl peroxide, 2-butanoneperoxide, tert-butyl perbenzoate, di-tert-butyl peroxide,2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, bis(tert-butylperoxyisopropyl)benzene, tert-butyl hydroperoxide, and the like.Presently preferred azo compounds contemplated for use in the practiceof the present invention include 2,2′-azobis(2-methylpropanenitrile),2,2′-azobis(2-methylbutanenitrile),1,1′-azobis(cyclohexanecarbonitrile), and the like.

Radiation free-radical cure initiators (or, photoinitiators) include forexample, those commercially available from Vantico, Inc., Brewster, NewYork under the tradename “IRGACURE” and “DAROCUR”, such as “IRGACURE”184 (1-hydroxycyclohexyl phenyl ketone), 907(2-methyl-1-[4-(methylthio)phenyl]-2-morpholino propan-1-one), 369[2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone], 500(the combination of 1-hydroxy cyclohexyl phenyl ketone andbenzophenone), 651 (2,2-dimethoxy-2-phenyl acetophenone), 1700 [thecombination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethyl pentyl)phosphineoxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one] and “DAROCUR” 1173(2-hydroxy-2-methyl-1-phenyl-1-propane) and 4265 (the combination of2,4,6-trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy2-methyl-1-phenyl-propan-1-one); photoinitiators available commerciallyfrom Dow Chemical under the “CYRACURE” tradename, such as “CYRACURE”UVI-6974 (mixed triaryl sulfonium hexafluoroantimonate salts) andUVI-6990 (mixed triaryl sulfonium hexafluorophosphate salts); and thevisible light [blue] photoinitiators, dl-camphorquinone and “IRGACURE”784DC.

Additional photoinitiators may be chosen from those available fromSartomer, Inc., Exton, Pa. under the tradenames “ESACURE” and “SARCAT”.Examples include “ESACURE” KB1 (benzil dimethyl ketal), “ESACURE” EB3(mixture of benzoin and butyl ethers), “ESACURE” TZT(trimethylbenzophenone blend), “ESACURE” KIP100F (hydroxy ketone),“ESACURE” KIP150 (polymeric hydroxy ketone), “ESACURE” KT37 (blend of:“ESACURE” TZT and KIP150), “ESACURE” KT046 (blend of triphenyl phosphineoxide, “ESACURE” KIP150 and TZT), “ESACURE” X33 (blend of 2- and4-isopropylthioxanthone, ethyl 4-(dimethyl amino)benzoate and “ESACURE”TZT], “SARCAT” CD 1010 [triaryl sulfonium hexafluoroantimonate (50% inpropylene carbonate)], “SARCAT” DC 1011 [triaryl sulfoniumhexafluorophosphate (50% n-propylene carbonate)], “SARCAT” DC 1012(diaryl iodonium hexafluoroantimonate), and “SARCAT” K185 [triarylsulfonium hexafluorophosphate (50% in propylene carbonate)].

Photoinitiators include triarylsulfonium and diaryliodonium saltscontaining non-nucleophilic counterions and aryl diazonium salts,examples of which include 4-methoxybenzenediazonium hexafluorophosphate,benzenediazonium tetrafluoroborate, diphenyl iodonium chloride, diphenyliodonium hexafluorophosphate, 4,4-dioctyloxydiphenyl iodoniumhexafluorophosphate, triphenylsulfonium tetrafluoroborate,diphenyltolylsulfonium hexafluorophosphate, phenylditolylsulfoniumhexafluoroarsenate, and diphenyl-thiophenoxyphenylsulfoniumhexafluoroantimonate.

Of course, combinations of such photoinitiators may be used as deemedappropriate by those of ordinary skill in the art.

As employed herein, the term “coupling agent” refers to chemical specieswhich contain one set of functional groups capable of bonding to mineraland/or organic surfaces and which 2-5, also contain another set ofreactive functional groups capable of bonding to the reactive materialsin the die attach adhesive material. Coupling agents thus facilitatelinkage of the die attach material to the substrate to which it isapplied.

Exemplary coupling agents contemplated for use in the practice of thepresent invention include silicate esters, metal acrylate salts (e.g.,aluminum methacrylate), titanates (e.g., titaniummethacryloxyethylacetoacetate triisopropoxide), or compounds thatcontain a copolymerizable group and a chelating ligand (e.g., phosphine,mercaptan, acetoacetate, and the like). Generally in the range of about0.1 up to 10 wt % of at least one coupling agent (based on the totalweight of the organic phase) will be employed, with the range of about0.5 up to 2 wt % being desirable.

Certain desirable coupling agents contain both a co-polymerizablefunction (e.g., vinyl moiety, acrylate moiety, methacrylate moiety,styrene moiety, cyclopentadiene moiety, and the like), as well as asilicate ester function. The silicate ester portion of the couplingagent is capable of condensing with metal hydroxides present on themineral surface of the substrate, while the co-polymerizable function iscapable of co-polymerizing with the other reactive components ofinvention adhesive composition. An example of such a coupling agent isan oligomeric silicate coupling agent, such aspoly(methoxyvinylsiloxane).

The pre-applied die attach adhesive material may further include in therange of about 20 up to 90 wt % filler, based on the total weight of thepre-applied die attach composition. Fillers contemplated for use in thepractice of the present invention may optionally be conductive(electrically and/or thermally). Electrically conductive fillerscontemplated for use in the practice of the present invention include,for example, silver, nickel, gold, cobalt, copper, aluminum, graphite,silver-coated graphite, nickel-coated graphite, alloys of such metals,and the like, as well as mixtures thereof. Both powder and flake formsof filler may be used herein. In flake form, the filler may have athickness of less than about 2 microns, with planar dimensions of about20 to about 25 microns. Flake employed herein may have a surface area ofabout 0.15 to 5.0 m²/g and a tap density of about 0.4 up to about 5.5g/cc. In powder form, the filler particles may have a diameter of about0.5 to 30 microns, such as about 20 microns.

When present, the filler typically is used from about 1 wt % to about 95wt % of the pre-applied die attach material, where wt % is based on thetotal weight of the composition.

Thermally conductive fillers contemplated for use herein include, forexample, aluminum nitride, boron nitride, silicon carbide, diamond,graphite, beryllium oxide, magnesia, silica, alumina, and the like.

Electrically and/or thermally conductive fillers should be renderedsubstantially free of catalytically active metal ions by treatment withchelating agents, reducing agents, nonionic lubricating agents, ormixtures of such agents. Such treatment is described in U.S. Pat. No.5,447,988, which is expressly incorporated by reference herein in itsentirety.

Optionally, a filler may be used that is neither electrically northermally conductive. Such fillers may be desirable to impart some otherproperty to the formulation such as, for example, reduced thermalexpansion of the cured composition, reduced dielectric constant,improved toughness, increased hydrophobicity, and the like. Examples ofsuch fillers include perfluorinated hydrocarbon polymers (i.e., TEFLON),thermoplastic polymers, thermoplastic elastomers, mica, fused silica,glass powder, spacer elements and the like.

The pre-applied die attach adhesive material may further contain otheradditives, such as defoaming agents, leveling agents, dyes, andpigments.

The die attach adhesive material may be applied to the semiconductorchip (see e.g. FIGS. 1-3) by stencil printing, screen printing or spraycoating to form the pre-applied die attach circuit chip. See FIGS. 4-6,respectively. In addition, the die attach adhesive material may beapplied to a substrate other than the semiconductor chip (see FIG. 9) bystencil printing, screen printing or spray coating to form thepre-applied die attach circuit chip. And the die attach adhesivematerial may be applied to an intermediate substrate, such as a waferdicing tape or film, a wafer supporting tape or film, which is used totransport the die attached adhesive material pre-applied on the tape orfilm for transfer onto the semiconductor chip or other substrate.

In the case of stencil printing or screen printing onto pre-dicedwafers, the wafers can be uniformly coated with the die attach adhesivematerial. During wafer dicing, the dicing saw then cuts completelythrough the pre-applied die attach adhesive material layer and thewafer.

In the case of stencil printing or screen printing onto pre-dicedwafers, the stencil or screen is made with apertures designed topartially, not completely, coat the individual die or semiconductorchips. Specifically, the webbing of the stencil or screen is used tomaintain the die attach adhesive material in place. That is, it isundesirable for the die attach adhesive material to enter into thedicing streets, which would facilitate die separation during dieplacement. The width of the webbing, or conversely, the dimensions ofthe aperture, are designed so that after die placement, the target wetbondline may be achieved and the die attach adhesive material may formfillets of the desired height beneath the die.

In the case of stencil printing or screen printing onto laminatesubstrates, the stencil or screen is made with apertures designed topartially coat the die pad. Specifically, the webbing of the screen orstencil is used to maintain in place the die attach adhesive materialafter die placement. The width of the webbing, or conversely, thedimensions of the aperture, are designed so that after die placement,the target wet bondline may be achieved and the pre-applied die attachadhesive material may form fillets of the desired height beneath the diewith minimal to no wetting by the pre-applied die attach adhesivematerial of the electrically conductive interconnects.

In the case of application onto laminate substrates, a “zero gapbondline” may be achieved with the die attach adhesive material. Forinstance, the laminate is first manufactured without a solder mask layerover the die pad. Thus, the die pad area is lower in height relative tothe non-die pad areas by a depth equal to the thickness of the soldermask layer, which is typically around 1 mil. These recessed die pads arethen filled with the die attach adhesive material, using stencilprinting or screen printing.

Preferably, an amount of die attach adhesive material is applied untilthe surface of the applied adhesive material is flush with the soldermask layer. The recessed die pad is not completely filled in with thedie attach adhesive material; rather, an amount of the die attachadhesive material is used such that after die placement, the die attachadhesive material has flowed underneath the die to cover the previouslyexposed die pad bottom. This method allows for semiconductor packagingmanufacturers to achieve thinner packages without changing the bondlineadhesive.

Where the die attach adhesive material is pre-applied on a substrateother than a semiconductor chip, the substrate may be a laminate (asnoted above), a ceramic, a lead frame, a heat slug or heat spreader (asnoted above), or an intermediate substrate (as also noted above).

Referring to FIG. 9, a die attach adhesive material 90A is pre-appliedonto a carrier substrate 70 to form a pre-applied die attach carriersubstrate 60A. When the bonding surface 68A of a semiconductor chip 62is brought into contact with the pre-applied die attach carriersubstrate 60A and electrical connections established, such as by way ofbonding wires 80 to electrical contact pads 76 on the carrier substrate70 from electrical contact pads 66 on the semiconductor chip 62, acircuit assembly 50 is formed.

In the case of spray coating, thin semiconductor wafers are desirablesubstrates on which to coat the die attach adhesive material. These thinsemiconductor wafers have thickness of about 2-3 mil. Althoughmechanically robust once properly supported, i.e., bonded onto flexiblesubstrates and encapsulated or overmolded, in their unsupported formthin dice derived from these wafers are fragile and break rather easily.It is therefore advantageous that a method for applying die attachadhesive material onto thin wafers apply minimal force while doing so.

After the die attach adhesive material has been applied onto the waferor die using any of the above methods, the adhesive material may then bedried to remove solvent, if present, or cooled to solidify the adhesivematerial.

A typical drying time may be about 30 minutes at a temperature of about100° C., though any temperature below the cure onset of the curablecomponents of the die attach adhesive material may be chosen. The lengthof time may vary depending on the time required for the surface of thedie attach adhesive material to become tack free at the chosentemperature.

Any time after the surface of the die attach adhesive material is tackfree (either by drying or cooling, or B-staging, as noted above), diebonding may occur.

Conditions suitable for curing the pre-applied die attach adhesivematerial, particularly one containing maleimide-, nadimide-, anditaconimide-containing compound include subjecting the pre-applied dieattach adhesive material to a temperature of at least about 175° C. butless than about 300° C. for about 0.5 up to about 2 minutes. A typicaldie bonding setting is a time of about 10 seconds at a temperature ofabout 100° C. using 500 cN spread, in the case of a 7.6 mm×7.6 mm die.This rapid, short duration heating can be accomplished in a variety ofways, e.g., with in-line snap cure stations such as those manufacturedby Nihon Sanso, a heated stage mounted on the diebonder, or an IR beamprovided by an EFOS Novacure IR unit. For a pre-applied die attachadhesive material containing a benzoxazine compound, the sametemperature conditions may be used to cure the adhesive material, thoughordinarily a longer time may be desirable, such as about 1 hour.

In the case of a stacked die assembly (such as described in U.S. Pat.Nos. 5,140,404, 5,286,679, 5,323,060, and 6,465,893, the disclosures ofeach of which being hereby expressly incorporated herein by reference),it is advantageous to heat the die before die placement in order to meltthe die attach adhesive material, particularly where a co-curablethermoplastic component is present, to allow for improved wetting of thesubstrate on which it is about to be placed. The die can be heated bypulsing heat through the die collet, which is an available feature infilm diebonders, such as those manufactured by ESC. In the case of thindie which are typically warped due to the build-up of residualmechanical stress during the grinding process, heating the die above acertain temperature has the effect of annealing the die and reducingwarpage.

FIGS. 8 and 10 depict a cross sectional view of two dies to be stackedin a stacked die assembly 110. The difference in this two configurationis that in FIG. 8 the die attach adhesive material 90 is pre-applied onthe lower surface 68 of the upper semiconductor chip 112 in the stackeddie assembly 110, whereas in FIG. 10 the die attach adhesive material90A is pre-applied on the upper surface 68 of the lower semiconductorchip 114 of the in the stacked die assembly 110A. Referring to FIG. 8,the stacked die assembly 110 includes a semiconductor chip in the formof pre-applied die attach circuit chip 112 (having chip die 62 andpre-applied die attach adhesive 90 disposed thereon), and another chipdie 62A, to which pre-applied die attach circuit chip 110 will beattached on handing surface 64A of chip die 62A. Pre-applied die attachcircuit chip 112 has bond pads 66 and bonding wires 80, to which becomeelectrically connected to chip die 62A by way of bonding pads 66A onchip die 62A. Bonding wires BOA extend from bond pads 66A, to eitheranother chip die (not shown) or a circuit board (not shown) forelectrical interconnection.

It is noted that chip die 62 as discussed herein may be provided as anindividual chip die, or may be provided as a chip scale package.Accordingly, in yet a further embodiment shown in FIG. 3, a circuitassembly 150 is provided including a chip scale package 160. Chip scalepackages are known in the art for use in electrical connections ofcircuits with circuit board substrates. In the present embodiment,circuit assembly 150 includes a structure similar to that shown in theembodiment depicted in FIG. 2, except that chip die 62 is replaced withchip scale package 160. For example, circuit assembly 150 includes acircuit board substrate 70 including contact pads 76 thereon. Substrate70 is attached to chip scale package 160, which may include, forexample, a chip die attached to a separate carrier substrate or aninterposer layer, as is known in the art. In such an embodiment, contactpads 66 and/or wires 80 may be provided on such a separate carriersubstrate or on the interposer layer, in a similar manner as set forthwith respect to circuit chip 60 in the previous description. Moreover,chip scale package 160 is attached to substrate 70 in a similar manneras with the previous description, through die attach material 90.

The invention also provides a method for adhesively attaching theinventive article of manufacture to a carrier substrate, such as a chipdie or a circuit board. The method includes:

a. providing the inventive article of manufacture;

b. providing a carrier substrate;

c. adjoining the inventive article of manufacture with the carriersubstrate to form an assembly where the inventive article of manufactureand the carrier substrate are separated by the pre-applied die attachadhesive material; and

d. exposing the so-formed assembly to a temperature condition sufficientto cure the pre-applied die attach adhesive material.

In another aspect of the invention, maleimides, itaconamides andnadimides possess a physical property profile which make them suitablefor use as an ILD used in the manufacture of silicon die. Oftentimes, intheir liquid form, these maleimides, itaconamides and nadimides have asufficiently low viscosity which enable spin coating. In addition, theirviscosity can be reduced further, if desired by heating or combiningwith a reactive diluent as discussed above, for spin coating thinnerILD's. Likewise, in the solid form, such maleimides, itaconamides andnadimides may be warmed or combined with dilueant to allow for spincoating. These maleimides, itaconamides and nadimides have a highthermal degradation temperature and high homopolymerization onset whichallows thinning by heating. Because the maleimides, itaconamides andnadimides are curable by exposure to radiation in the electromagneticspectrum, such as UV, photolithography to some resolution may beachieved. The cured products of the maleimides, itaconamides andnadimides have a sharp thermal degradation point, which allows for cleanand sharp laser ablation.

FIG. 7 shows in cross-section a semiconductor chip 100, in which a layerof ILD 108 is shown between a first and a second conductor 106A. Morespecifically, the semiconductor chip 100 is formed from a siliconsubstrate 102, which has been exposed to elevated temperature conditionsin an oxidizing atmosphere such that a layer 104 of silicon oxide formsas a semiconductor layer 104 thereover. The semiconductor layer 104shows a source of electrons 103, as well as a drain for electrons 103A,together with a gate 107, which controls the flow of electrons byregulating voltage. The layer 105 disposed over the semiconductor layeris made in this figure from borophosphosilicate glass, which may beapplied by a chemical vapor deposition process. Since the semiconductorlayer 104 is formed with an irregular surface, thisborophosphorosilicate glass surface planes those irregularities. Thenext layer shown is a first conductive layer 106, here shown as beingconstructed from copper. This conductor layer 106 may have a dissipationbarrier coated thereover (not shown). On top of the first conductivelayer 106 is a layer of ILD, on top of which is a second conductivelayer 106A. Finally In FIG. 7 is shown a passivation layer 101. Thepassivation layer 101 is often spin coated. Between the secondconductive layer 106A and a first conductive layer 106 is a via 109A,which has been formed through the layer of ILD 108 such that electronscan flow. And, between the first conductive layer 106 and thesemiconductor layer 106A is another via 109 for the same purpose.

Thus, broadly speaking the invention in this aspect provides asemiconductor chip, which includes a silicon substrate, semiconductorlayer, at least two conductor layers, between two of which is aninterlayer dielectric comprising one or more maleimide-, itaconamide- ornadimide-containing compound(s), or one or more benzoxazine-containingcompounds).

The invention will now be described in greater detail by reference tothe following non-limiting examples.

EXAMPLES

In a first example, a die attach adhesive material was prepared forpre-application to a semiconductor chip using the styrene-butadieneblock copolymer, KRATON D-1102, as a thermoplastic elastomericcomponent, and octadecylmaleimide and X-BMI (the 1,20-bismaleimidoderivative of 10,11-dioctyl-eicosane, as maleimides. The die attachedadhesive material for pre-application was prepared from the componentsrecited below in Table 1.

TABLE 1 Octadecylmaleimide 1.0 g KRATON D-1102 2.5 g X-BMI¹ 1.5 g RICON130² 0.2 g Silane coupling agent³ 0.2 g Dicumyl peroxide 0.05 g  Xylene5.0 g TEFLON filler 6.9 g ¹X-BMI (the 1,20-bismaleimido derivative of10,11-dioctyl-eicosane), was prepared according to the procedure setforth in U.S. Pat. No. 5,973,166, the disclosure of which is herebyexpressly incorporated herein by reference. ²Polybutadiene 20% graftedwith maleic anhydride (Sartomer) ³Proprietary silane-containing couplingagent.

Octadecylmaleimide was dissolved in xylene, and KRATON D-1102 was addedand allowed to dissolve before the remaining components were added.

A film was cast onto a glass substrate and dried overnight. A silicondie was then placed onto the film, and the film-coated substrate washeated to a temperature of 80° C. for 1 to 3 seconds. This assembly wasfinally cured at a temperature of 80° C. for 30 minutes.

The film die attach composition was evaluated for room temperature dieshear and hot die shear on a calibrated Dage 2400 die shear tester. Theresults are shown below in Table 2, compared to QMI536, a die attachproduct, commercially available from Henkel Loctite Corporation,LaJolla, Calif., which includes the same combination of bismaleimides asemployed above. Also included in Table 2 are die shear values after thecured composition was subjected to conditions of 85° C./85% humidity fora period of time of 24 hrs.

TABLE 2 Room Temperature Die Shear Hot Die Shear (245° C.) Formulations(lbs) (lbs) QMI536, initial 59.1 24.4 Formulation 1, initial 88.9 25.9QMI536, 24 hrs. 52.6 23.9 85/85 Formulation 1, 24 hrs. 79.6 24.6 85/85

The results shown above demonstrate that Formulation 1 has superior dieshear strength compared to an analogous flowable die attach composition,not in a pre-applied, non-flowable form.

In a second example, two samples were prepared using abenzoxazine-containing compound for the die attach material. Theconstituents of each of Formulations 2 and 3 are set forth below inTable 3 by parts.

TABLE 2 Benzoxazine⁴ 2 1.5 RICON 130² 0.2 0.2 Silane coupling agent³ 0.10.1 Resin⁵ 0.5 0.5 Epoxy⁶ — 0.5 Acetone 2 2 TEFLON filler 2 2.2⁴believed to have been made from bisphenol F, thiodiphenol, aniline andformaldehyde, and is available from Vantico under trade designation XU3560 US. ⁵Proprietary hydroxy functionalized aromatic resin. ⁶ARALDITE7097US.

Formulations 2 and 3 were prepared as follows. The benzoxazine wasdissolved in acetone at room temperature, together with the epoxy (forFormulation 3). To this was added with mixing at room temperature theresin, the RICON 130 and the silane coupling agent. Finally, the TEFLONfiller was added and thoroughly mixed to form a smooth, creamy paste.

Like Formulation 1, Formulations 2 and 3 were cast film onto glassslides. The glass slides coated with Formulations 2 and 3 were exposedto a temperature in the range of 95 to 125° C. for a period of time ofabout 10 to 60 minutes, and allowed to cool to room temperature. Once atroom temperature, a semiconductor chip was placed over eachformulation-coated glass slide, and the chip and substrate were togetherunder a temperature of 95 to 125° C. to attach the chip to thesubstrate. The formulations were then cured at a temperature of 175° C.for a period of time of 1 hour.

Once cured, Formulations 2 and 3 were evaluated for shear strength.Thus, 300 mil die on glass attached by Formulation 2 exhibited 62.8 Kg-fat room temperature, and 3.3 Kg-f at a temperature of 245° C., and thoseattached by Formulation 3 exhibited 56.4 Kg-f at room temperature, and2.7 Kg-f at a temperature of 245° C.

Formulations 2 and 3 were also subject to differential scanningcalorimetery in order to determine their onset temperatures, cure peaksand a cured energy. Formulations 2 was observed to have an onsettemperature of 190° C., whereas Formulation 3 was observed to have anonset temperature of 195° C. Formulation 2 demonstrated a cure peak of214° C., whereas Formulation 3 demonstrated a cured peak of 222° C.Formulation 2 also demonstrated a cure energy of 171.75 J/g, whereasFormulation 3 showed a cure energy of 91.7 J/g.

1. A semiconductor chip comprising: a silicon substrate; a semiconductorlayer; at least two conductor layers, between at least two of which isan interlayer dielectric comprising one or more maleimide-, itaconamide-or nadimide-containing compound(s).
 2. The semiconductor chip accordingto claim 1, wherein the maleimide-, nadimide- or itaconimide-compound(s)comprise(s)

respectively, wherein: m=1-15, p=0-15, each R² is independently selectedfrom hydrogen or lower alkyl, and J comprises a monovalent or apolyvalent moiety comprising organic or organosiloxane radicals, andcombinations of two or more thereof.
 3. The semiconductor chip accordingto claim 1, wherein J comprises a branched chain alkyl, alkylene,alkylene oxide, alkylene carboxyl or alkylene amido species havingsufficient length and branching to render the maleimide, nadimide and/oritaconimide compound a liquid, and m is 1, 2 or
 3. 4. The semiconductorchip according to claim 1, wherein the maleimide-containing compound,the nadimide-containing compound or the itaconimide-containing compoundcomprises structures I, II or III, respectively, wherein m=1-6, p=0, R²is independently selected from hydrogen or lower alkyl, and J is amonovalent or polyvalent radical selected from hydrocarbyl, substitutedhydrocarbyl, heteroatom-containing hydrocarbyl, substitutedheteroatom-containing hydrocarbyl, hydrocarbylene, substitutedhydrocarbylene, heteroatom-containing hydrocarbylene, substitutedheteroatom-containing hydrocarbylene, polysiloxane,polysiloxane-polyurethane block copolymer, and combinations of two ormore thereof, optionally containing one or more linkers selected fromthe group consisting of a covalent bond —O—, —S—, —NR—, —O—C(O)—,—O—C(O)—O—, —O—C(O)—NR—, —NR—C(O)—, —NR—C(O)—O—, —NR—C(O)—NR—, —S—C(O)—,—S—C(O)—O—, —S—C(O)—NR—, —S(O)—, —S(O)₂—, —(O)—S(O)₂—, —O—S(O)₂—O—,—O—S(O)₂—NR—, —O—S(O)—, —O—S(O)—O—, —O—S(O)—NR—, —O—NR—C(O)—,—O—NR—C(O)—O—, —O—NR—C(O)—NR—, —NR—O—C(O)—, —NR—O—C(O)—O—,—NR—O—C(O)—NR—, —O—NR—C(S)—, —O—NR—C(S)—O—, —O—NR—C(S)—NR—, —NR—O—C(S)—,—NR—O—C(S)—O—, —NR—O—C(S)—NR—, —O—C(S)—, —O—C(S)—O—, —O—C(S)—NR—,—NR—C(S)—, NR—C(S)—O—, —NR—C(S)—NR—, —S—S(O)₂—, —S—S(O)₂—O—,—S—S(O)₂—NR—, —NR—O—S(O)—, —NR—O—S(O)—O—, —NR—O—S(O)—NR—, —NR—O—S(O)₂—,—NR—O—S(O)₂—O—, —NR—O—S(O)₂—NR—, —O—NR—S(O)—, —O—NR—S(O)—O—,—O—NR—S(O)—NR—, —O—NR—S(O)₂—O—, —O—NR—S(O)₂—NR—, —O—NR—S(O)₂—,—O—P(O)R₂—, —S—P(O)R₂—, —NR—P(O)R₂—, wherein each R is independentlyhydrogen, alkyl or substituted alkyl, and combinations of any two ormore thereof.
 5. A semiconductor chip comprising: a silicon substrate; asemiconductor layer; at least two conductor layers, between at least twoof which is an interlayer dielectric comprising one or morebenzoxazine-containing compound(s).
 6. The semiconductor chip accordingto claim 5, wherein the benzoxazine component comprises

wherein: L is a member selected from the group consisting of an alkyleneor a siloxane linking moiety, hydrogen, a direct bond, O, C═O, S, O═S═O,C, CH, CH₂, and CR⁹R¹⁰, wherein R⁹ and R¹⁰ are alkyl, halogensubstituted alkyl, aryl or alkaryl; Ar is optionally substitutedarylene; Q is an oxazine ring or amine salt thereof having thestructure:

and is bonded to Ar in a fused manner at positions 5 and 6 of theoxazine ring, wherein: Sp is optional, and if present, is a C₁ to C₆alkylene spacer, n is 1 or 2, m is 1 to 4, x and y are eachindependently 0 to 4, and at least one of R¹¹, R¹², or R¹³ is apolymerizable moiety.
 7. The semiconductor chip according to claim 5,wherein the benzoxazine component comprises

wherein o is 1-4, X is a direct bond (when o is 2), alkyl (when o is 1),alkylene (when o is 2-4), carbonyl (when o is 2), thiol (when o is 1),thioether (when o is 2), sulfoxide (when o is 2), and sulfone (when o is2), and R¹⁴ is alkyl or aryl.
 8. The semiconductor chip according toclaim 5, wherein the benzoxazine component comprises

wherein X is selected from the group consisting of a direct bond, CH₂,C(CH₃)₂, C═O, S═O and O═S═O, S, and R¹⁴ and R¹⁵ are the same ordifferent and are selected from methyl, ethyl, propyls, or butyls andaryl.
 9. The semiconductor chip according to claim 5, wherein thebenzoxazine component is a member selected from the group consisting of:

wherein R¹⁴, R¹⁵ and R¹⁶ are the same or different and are membersselected from the group consisting of methyl, ethyl, propyls, butyls andaryl.
 10. The semiconductor chip according to claim 5, wherein thebenzoxazine component is a member selected from the group consisting of: